Intersection Theory on Linear Subvarieties of Toric Varieties

We give a complete description of the cohomology ring $A^*(\overline Z)$ of a compactification of a linear subvariety $Z$ of a torus in a smooth toric variety whose fan $\Sigma$ is supported on the tropicalization of $Z$. It turns out that cocycles on $\overline Z$ canonically correspond to Minkowski weights on $\Sigma$ and that the cup product is described by the intersection product on the tropical matroid variety $\operatorname{Trop}(Z)$.Comment: published versio

How do Ontology Mappings Change in the Life Sciences?

Mappings between related ontologies are increasingly used to support data integration and analysis tasks. Changes in the ontologies also require the adaptation of ontology mappings. So far the evolution of ontology mappings has received little attention albeit ontologies change continuously especially in the life sciences. We therefore analyze how mappings between popular life science ontologies evolve for different match algorithms. We also evaluate which semantic ontology changes primarily affect the mappings. We further investigate alternatives to predict or estimate the degree of future mapping changes based on previous ontology and mapping transitions.Comment: Keywords: mapping evolution, ontology matching, ontology evolutio

Master stability functions reveal diffusion-driven pattern formation in networks

We study diffusion-driven pattern-formation in networks of networks, a class of multilayer systems, where different layers have the same topology, but different internal dynamics. Agents are assumed to disperse within a layer by undergoing random walks, while they can be created or destroyed by reactions between or within a layer. We show that the stability of homogeneous steady states can be analyzed with a master stability function approach that reveals a deep analogy between pattern formation in networks and pattern formation in continuous space.For illustration we consider a generalized model of ecological meta-foodwebs. This fairly complex model describes the dispersal of many different species across a region consisting of a network of individual habitats while subject to realistic, nonlinear predator-prey interactions. In this example the method reveals the intricate dependence of the dynamics on the spatial structure. The ability of the proposed approach to deal with this fairly complex system highlights it as a promising tool for ecology and other applications.Comment: 20 pages, 5 figures, to appear in Phys. Rev. E (2018

From Tahrir Square to Open Space: Practical Experiences with Open Space Technology in Egypt

The Egyptian revolution started literally with an open space: at the Tahrir Square in the heart of Cairo. Here it was where many Egyptians for the first time in their lives made the experience of freely talking about politics in public. Since January 2011, many young Egyptians are trying to keep up this “Tahrir experience” by experimenting with new forms of political debate and civic education in Egypt. It was this spirit that resulted in the idea of introducing the Open Space Technology (OST) as a new format of civic education in Egypt. In March 2011 the authors of this article, both working in Egypt for many years, organized the first Open Space in the country. This event encouraged many other national and international institutions and initiatives to adopt and further develop OST in Egypt and other Arab countries. The unexpected popularity of OST in revolutionary Egypt proved that it is in fact the right methodology at the right time in the right context and the right place. OST is a meeting format that fosters dialogue and exchange in a democratic way. It is easy to organize and non-costly. It invites for sharing opinions, discovering common ground, discussing and tackling differences. It helps generating ideas and reflecting about their implementation. This article argues that Open Space (OS), therefore, is a format that perfectly fits the transforming political environment and the socio-cultural setting of Egypt and – most probably – other Arab transformation-states